U.S. patent application number 09/745873 was filed with the patent office on 2001-06-28 for method for dynamic allocation of channels in a code divison multiple access packet data system.
This patent application is currently assigned to LG Electronics, Inc.. Invention is credited to Lee, Seoung-Young.
Application Number | 20010005378 09/745873 |
Document ID | / |
Family ID | 19628481 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010005378 |
Kind Code |
A1 |
Lee, Seoung-Young |
June 28, 2001 |
Method for dynamic allocation of channels in a code divison
multiple access packet data system
Abstract
A CDMA packet data system is disclosed that can dynamically
allocate channels in the CDMA packet data system. Using the
disclosed dynamic allocation method, the utilization efficiency of
multiple channels is increased and the transmission rate of packet
data is increased. This is because a static, specific channel is
not allocated to each terminal, but rather the system dynamically
allocates multiple channels to each mobile terminal. Thus, the base
station provides information on all channels used in the system to
multiple terminals. The terminals check the occupied state of each
channel before transmitting packet data, and thereafter
transmitting packet data through an unoccupied channel.
Inventors: |
Lee, Seoung-Young;
(Kyoungki-Do, KR) |
Correspondence
Address: |
FLESHNER & KIM
P.O. Box 221200
Chantilly
VA
20153-1200
US
|
Assignee: |
LG Electronics, Inc.
|
Family ID: |
19628481 |
Appl. No.: |
09/745873 |
Filed: |
December 26, 2000 |
Current U.S.
Class: |
370/459 ;
370/342; 455/452.1 |
Current CPC
Class: |
H04J 13/16 20130101;
H04W 48/08 20130101; H04W 72/04 20130101; H04B 7/2628 20130101;
H04W 72/12 20130101 |
Class at
Publication: |
370/459 ;
370/342; 455/452 |
International
Class: |
H04B 007/216 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 1999 |
KR |
60778/1999 |
Claims
What is claimed is:
1. A method allocating channels in a CDMA packet data system,
comprising: providing channel availability information for each of
a plurality of channels from a base station to each of a plurality
of terminals; dynamically allocating available channels to
corresponding ones of the plurality of terminals to allow the
transmission of packet data according to the available or
unavailable state of each channel; transmitting a state signal from
the base station over each of the allocated channels indicating the
unavailable state of the allocated channels.
2. The method of claim 1, wherein the base station transmits
information containing all PN codes used by the base station to
each one of the plurality of terminals.
3. The method of claim 1, wherein the step of dynamically
allocating the available channels comprises: simultaneously
monitoring each of the plurality of channels in parallel to detect
whether the state signal indicating channel availability is
transmitted by the base station over any of the plurality of
channels; sending the packet of data through an idle channel, if an
idle channel signal is detected; waiting until an idle channel is
available, if an occupied channel signal is detected.
4. The method of claim 3, wherein the step of simultaneously
monitoring each of the plurality of channels comprises detecting on
each channel one of a power control signal and an idle signal,
wherein the power control signal is the occupied channel signal
indicating unavailability of the channel, and the idle channel
signal indicates channel availability.
5. The method of claim 1, wherein the step of transmitting a state
signal from the base station comprises: transmitting a power
control signal through a downward link channel corresponding to the
allocated channel through which the packet of data is transmitted
when synchronization is acquired using a preamble of the data
packet; and transmitting a channel occupancy release signal through
the downward link channel corresponding to the allocated channel
through which the data packet was transmitted when the data packet
has been fully received.
6. The method of claim 1, wherein each of the available channels
are dynamically allocated to different ones of the plurality of
terminals.
7. The method of claim 6, wherein each one of the plurality of
channels comprises a traffic channel and a signaling channel, and
wherein the data packets are transmitted over the data channel and
the state signal is transmitted over the signaling channel.
8. A method for transmitting packet data by dynamically allocating
channels in a communication system, comprising: determining which,
if any, of a plurality of communication channels is in an occupied
state using a corresponding plurality of PN codes; and one of
transmitting a data packet through a dynamically allocated
unoccupied one of the plurality of channels for transmission and
monitoring each one of the plurality of channels to determine when
the occupied state of one of the plurality of channels is released,
if there is no channel in the unoccupied state.
9. The method of claim 8, wherein the step of determining the
occupied state comprises simultaneously multiplying the PN code for
each channel by a signal received from a base station.
10. The method of claim 9, wherein the multiplication is performed
at a rate equal to a power control signal transmission rate of the
base station.
11. The method of claim 8, wherein the step of transmitting the
data packet comprises: determining that a channel using a
prescribed one of the plurality of PN codes is in an idle state and
transmitting the data packet on the idle channel, if a base station
transmits an idle signal on the channel; determining that each one
of the plurality of channels is in an occupied state and waiting
until one of the plurality of channels becomes idle if the base
station transmits a power control signal on each channel.
12. The method of claim 11, wherein a signal transmitted from the
base station is multiplied by each one of the plurality of PN codes
to determine if the channel associated with a prescribed one of the
PN codes is occupied or idle.
13. The method of claim 12, wherein a power control signal
transmitted on a channel indicates that the channel is
occupied.
14. The method of claim 12, wherein each channel has a unique PN
code.
15. The method of claim 12, wherein each channel comprises a
signaling channel and a traffic channel.
16. The method of claim 11, wherein a terminal transmitting the
data packet has stored in the terminal the PN code for each one of
the plurality of channels.
17. A method for informing a plurality of terminals of the occupied
or unoccupied state of channels of a CDMA system, comprising:
providing a unique PN code for each one of a plurality of channels
used in the CDMA system from a base station to each one of a
plurality of terminals in communication with the base station;
transmitting a power control signal over an occupied channel using
the PN code of the occupied channel; and transmitting an idle
signal over an idle channel using the same PN code as the idle
channel.
18. The method of claim 17, wherein the power control signal is
transmitted on a channel when the base station acquires
synchronization and phase of a data packet transmitted by one of
the plurality of terminals, and wherein the idle signal is then
transmitted on the channel when the base station has received the
entire packet of data.
19. The method of claim 18, wherein each one of the plurality of
terminals has stored therein the unique PN code of each one of the
plurality of channels.
20. A method allocating channels in a CDMA packet data system,
comprising: receiving channel availability information for each of
a plurality of channels from a base station; dynamically allocating
an available channel and transmitting a packet of data to the base
station using the allocated channel; receiving from the base
station a power control signal on the allocated channel.
21. The method of claim 20, wherein the power control signal is
released when the data packet has been transmitted.
22. The method of claim 20, wherein the power control signal
indicates unavailability of the channel.
23. The method of claim 22, wherein a plurality of terminals are
configured to simultaneously monitor channel availability
information for all channels of the base station and transmit data
on the first available channel detected.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a Code Division Multiple
Access (CDMA) packet data system, and more particularly, to a
method for dynamic allocation of channels in a CDMA packet data
system.
[0003] 2. Background of the Related Art
[0004] Generally, a CDMA transmitter transmits data by multiplying
a PN (Pseudo Noise) code after spreading the spectrum of the
transmit frequency, and a CDMA receiver demodulates the data to the
original bandwidth by multiplying the same PN code as that in
transmission.
[0005] FIG. 1 illustrates a block diagram of a related art CDMA
packet data system. The system includes a base station 20 and a
plurality of terminals 1-N.
[0006] The plurality of terminals 1-N are typically grouped in as
many groups as there are channels used in one base station 20.
Channels in the CDMA system are distinguished by unique PN codes.
For example, if a system has six terminals 1-6 (i.e., N is 6) and
three channels in one base station 20, this base station 20
classifies the six terminals 1-6 into three groups. Each group uses
one channel.
[0007] Terminals using the same channel (terminals in the same
group) each monitor the occupied state of the channel in order to
prevent collisions with data transmitted by other terminals in the
channel. Thus, if one terminal in a group detects that the other
terminals in the same group (and thus using the same PN code as
that used by itself) are not currently occupying the channel, it
starts to transmit data through the channel. In determining whether
or not the channel is occupied, an idle signal transmitted from the
base station to the terminal is used.
[0008] In the related art system, the terminal has to transmit
packet data through the corresponding, pre-allocated channel, and
cannot use other channels. This method for static allocation of
channels in the related art CDMA packet data system will now be
described in more detail.
[0009] If the number of channels used in the base station 20 is
three, and there are six terminals 1-6 for this base station 20,
the base station 20 allocates a channel to each terminal 1-6. For
example, channel A is allocated to terminal 1, terminal 2, and
terminal 3, channel B is allocated to terminal 4, and channel C is
allocated to terminal 5 and terminal 6.
[0010] Terminals in each channel can access the base station 20
independently of other channels. The CDMA system distinguishes
channels using a PN seed. That is, terminal 1, terminal 2, and
terminal 3 use the same PN seed, but the terminals in channel A and
the terminal in channels B and C use different PN seeds.
[0011] With respect to channel A, as shown in FIG. 2, terminal 1
detects whether or not channel A is in the idle state in step ST1.
If it is determined that channel A is idle, terminal 1 transmits
packet data through channel A, as shown in step ST2.
[0012] If a packet of data to be transmitted by terminal 3 is
generated after terminal 1 transmits one packet of data in this
way, terminal 3 also detects whether or not channel A is in the
idle state, according to step ST1. If channel A is idle, the packet
of data of terminal 3 is transmitted through channel A, as shown in
step ST2.
[0013] In this way, terminal 1, terminal 2, and terminal 3 each
transmit data packets through channel A without collision with
other data at different time intervals in a uniform order.
[0014] With respect to channel B and channel C, data is transmitted
without collision with other data in the same way as described for
channel A.
[0015] A method of detecting the occupied state of a channel in the
related art system will now be described. Generally, packet data
transmitted from a terminal consists of a preamble and data. The
preamble is used by the base station in order to acquire the
synchronization and phase of data transmitted from the
terminal.
[0016] When terminal 1 transmits a packet of data to the base
station 20 through channel A, the base station 20 transmits a power
control signal through channel A to terminal 1. This enables
terminal 1 and the base station 20 to maintain a constant power
after acquiring synchronization and phase using the preamble of the
packet data. Therefore, terminal 1 performs power control using
this power control signal, and the other terminals (terminal 2 and
terminal 3) not transmitting packet data do not transmit data
because they recognize this power control signal as a channel
occupancy signal.
[0017] Once the packet data has been received through channel A,
the base station 20 does not perform power control any more.
Instead, it but transmits an idle signal to the terminal side
through channel A. Therefore, the terminals (terminal 1, terminal
2, and terminal 3) allocated to channel A detect that channel A is
not occupied, and a terminal of that channel having packet data to
be transmitted thus transmits data.
[0018] This method of channel allocation has various problems. For
example, terminal 4 (allocated to channel B) and terminals 5 and 6
(allocated to channel C) cannot access channel A. In addition, the
terminals allocated to channel A cannot access channel B or channel
C. Thus, when channel A is busy and channel B is idle, the
terminals allocated to channel A cannot use channel B.
[0019] Additionally, in this method for static allocation of
channels in the related art CDMA packet data system, since channels
are allocated in advance before the terminals transmit packet data
and packet data is transmitted using only the allocated channel,
the efficiency of the channel is decreased because the traffic of
the channel is non-uniformly distributed.
[0020] Additionally, in some systems, when a prescribed period of
time elapses after the occurrence of the traffic, the base station
checks the traffic state for a period of time, and reallocates a
predetermined number of terminals to the channel. However, this
method has the disadvantage in that the non-uniformity of the
traffic cannot be solved right away, and requires that the traffic
state be checked.
[0021] The above references are incorporated by reference herein
where appropriate for appropriate teachings of additional or
alternative details, features and/or technical background.
SUMMARY OF THE INVENTION
[0022] An object of this invention is to provide a method of
allocating channels in a CDMA system which substantially obviates
the problems caused by disadvantages in the related art.
[0023] Another object of the present invention is to provide a
method for dynamic allocation of channels in a CDMA packet data
system which increases the utilization efficiency of multiple
channels.
[0024] Another object of the present invention is to provide a
method for dynamic allocation of files in a CDMA packet data system
that increases the transmission rate of packet data by dynamically
selecting a channel for each terminal according to the occupied
state of the channels.
[0025] Another object of the present invention is to provide a
method for dynamic allocation of channels in a CDMA packet data
systems that increases the utilization efficiency of multiple
channels and the transmission rate of packet data by not allocating
a static, specific channel to one terminal.
[0026] Another object of the present invention is to provide a CDMA
packet data transfer method that dynamically allocates multiple
channels to a single terminal and to provide information on all
channels used in the system to multiple terminals in communication
with a base station, checking the occupied state of each channel by
a terminal desired to transmit packet data, and thereafter
transmitting packet data through an unoccupied channel.
[0027] To achieve these objects, in whole or in parts, there is
provided a method for dynamic allocation of channels in a CDMA
packet data systems having a first step wherein a base station
provides information of all channels used in the system to each
terminal; a second step wherein the terminal provided with the
information of all channels dynamically allocates the channels
according to the occupied or unoccupied state of each channel for
thereby transmitting one packet data; and a third step wherein the
base station receiving the packet data transmits a signal reporting
the occupied state of each channel to the terminal through the
channel through which the packet data is transmitted.
[0028] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objects and advantages
of the invention may be realized and attained as particularly
pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The invention will be described in detail with reference to
the following drawings in which like reference numerals refer to
like elements wherein:
[0030] FIG. 1 is a block diagram illustrating the construction of a
related art CDMA packet data system;
[0031] FIG. 2 is a flow chart illustrating a related art method of
determining channel allocation wherein each terminal transmits
packet data using a statically allocated channel;
[0032] FIG. 3 is a drawing illustrating packet data transmission
using a statically allocated channel in a CDMA packet data system
according to the related art;
[0033] FIG. 4 is a flow chart illustrating a method for dynamic
allocation of channels in a CDMA packet data system according to a
preferred embodiment of the present invention; and
[0034] FIG. 5 is a drawing illustrating an example of a packet data
transmission using a statically allocated channel according to the
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0035] In a preferred embodiment of the present invention, a
terminal is not allocated to a specific channel. The terminal
transmits packet data not only through a specific channel, but
through all channels used in the system.
[0036] Thus, when an arbitrary terminal is powered on, the base
station 10 transmits information containing all PN codes used in
the system to the powered-on terminal. Consequently, the terminal
has all PN codes used in the system available to it. Each terminal
in the base station 10 can then implement a packet data
transmission process over any channel.
[0037] FIG. 4 illustrates a method wherein an arbitrary terminal
transmits packet data by dynamic allocation of channels. As
illustrated therein, a terminal commencing transmission of packet
data first sequentially determines if all of the system channels
are occupied by using all of the transmitted PN codes (steps ST11,
ST12, and ST13). Next, if it is determined that there is a channel
in an unoccupied state, the terminal transmits packet data through
that channel. If no channels are available, however, the terminal
waits until the occupied state is released (steps ST14, ST15, and
ST16).
[0038] The method for transmitting packet data by dynamic
allocation of channels by a terminal will now be described in
further detail.
[0039] The terminal commencing packet data transmission first
checks whether or not all of the channels used in the system are in
the occupied state, by using all of the pretransmitted PN codes at
once, as shown in steps ST11, ST12, and ST13. In other words, the
terminal detects whether a power control signal (signal for
informing channel occupation) or an idle signal (channel occupancy
release signal) is transmitted from each channel. This is done
simultaneously by monitoring all of the channels in a parallel
mode.
[0040] If the terminal determines that there is an idle channel,
the terminal sends packet data through the available channel. If,
however, there is no idle channel, the terminal waits until an idle
channel is generated, as shown in steps in ST14, ST15, and
ST16.
[0041] FIG. 5 illustrates the channel allocation method according
to the preferred embodiment. Referring to FIG. 5, there is depicted
an exemplary situation where there is one base station 10 and six
terminals 1 through 6. The number of channels used in the system is
three, to wit, A, B, and C. Terminal 1 simultaneously monitors
channel A, channel B, and channel C in parallel mode. At this time,
since there is no terminal using any of the channels, the base
station 10 preferably transmits an idle signal through all
channels.
[0042] Therefore, when terminal 1 commences a data packet
transmission, it can transmit the packet data immediately. The
transmitted packet data includes a preamble and data. The preamble
is used so that the base station acquires phase and
synchronization.
[0043] The base station thus acquires phase and synchronization
upon receipt of the preamble in the packet data, and thereafter
transmits a power control signal to the terminal, to control the
power of the terminal. The power control signal is preferably
transmitted through the channel in which the packet data is being
transmitted. At this time, since the base station implements the
power control of a mobile station (terminal) in units of 1 msec, a
signal indicating whether the channel is occupied is transmitted to
the terminal. Thus, the terminal should preferably monitor whether
the channel is occupied in units of 1 msec. In addition, when the
packet of data has been received, an idle signal indicating the
release of channel occupancy is generated.
[0044] In order for terminal 5 to send packet data, it preferably
monitors whether channel A, channel B, and channel C are occupied
every 1 msec. Thus, the occupied state of channel A is detected
using a first PN code (PN A), the occupied state of channel B is
detected using a second PN code (PN B), and the occupied state of
channel C is detected using a third PN code (PN C). Therefore, if
it is determined that a power control signal is currently being
broadcasted, the channel is deemed to be in the occupied state. If,
however, it is determined that an idle signal is being broadcasted,
the channel is deemed to be in the idle state.
[0045] Referring to the example depicted in FIG. 5, as a result of
detecting whether or not each channel is occupied, channel A is in
the occupied state because it is used by terminal 1. Channel B,
however, is in the idle state, so terminal 5 transmits packet data
through channel B.
[0046] Similarly, when terminal 4 is about to send packet data, it
checks the occupied state of channel A, channel B, and channel C.
At this time, as illustrated in FIG. 5, if channel A and channel B
are in the occupied state and channel C is in the idle state,
terminal 4 transmits packet data using channel C.
[0047] Next, when terminal 3 is about to send packet data, it
continues to monitor the state of the channels because all the
channels are in the occupied state. Thus, it searches for an idle
channel. When channel A completes the transmission of one packet
data, the base station 10 stops the power control over channel A,
and transmits an idle signal. Hereupon, terminal 3 transmits packet
data through channel A.
[0048] In this manner, each terminal 1 through 6 checks the
occupied state of all channels used in the system, and thereafter
transmits packet data by dynamic utilization of an idle
channel.
[0049] The channel that the terminal uses to detect whether a
channel is occupied and the channel that the base station uses to
transmit a signal to indicate whether a channel is occupied are the
same signaling channel.
[0050] In addition, when the terminal transmits packet data to the
base station, a traffic channel is preferably used, and when the
base station transmits a power control signal for the power control
of the terminal, a signaling channel is preferably used. They still
use the same PN code. However, it is assumed that the same channel
means the same PN code to help in understanding the description of
the invention.
[0051] As described above, in the method for dynamic allocation of
channels in a CDMA packet data system according to the preferred
embodiment has many advantages. For example, the utilization
efficiency of multiple channels is increased and the transmission
rate of packet data is increased by dynamically allocating multiple
channels to each terminal by providing information on all channels
used in the system, respectively, to multiple terminals in
communication with the base station, checking the occupied state of
each channel by a terminal desired to transmit packet data, and
thereafter transmitting packet data through an unoccupied
channel.
[0052] In addition, when the occupied or unoccupied state of all
channels used in the system is detected, the time taken for the
detection is reduced irrespective of the number of channels by
detecting the occupied or unoccupied state of all channels in a
parallel mode at one time.
[0053] The foregoing embodiments and advantages are merely
exemplary and are not to be construed as limiting the present
invention. The present teaching can be readily applied to other
types of apparatuses. The description of the present invention is
intended to be illustrative, and not to limit the scope of the
claims. Many alternatives, modifications, and variations will be
apparent to those skilled in the art. In the claims,
means-plus-function clauses are intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures.
* * * * *